For example, in a power generation system that uses a piezoelectric element, the power is generated by arranging a terminal of a plate-like piezoelectric element to vibrate through an external stress and to resonate a free terminal to deform the piezoelectric element, or by impacting the plate-like piezoelectric element with a steel material to cause some deformation of the piezoelectric element.
The author of the present application has found that a problem resides in the power generation technique using the piezoelectric element as have been described above.
More specifically, in a power generation system that uses a plate-like piezoelectric element, while the power is generated by deforming the plate-like piezoelectric element through mechanical vibrational energy, externally driven vibration needs to be aligned with the deforming direction of the piezoelectric element, and efficient power generation cannot be achieved when the externally driven vibration is misaligned with the deforming direction of the piezoelectric element at the time of installation, or when the direction of the externally driven vibration occasionally changes.